At&t promised account credit not issued (ATTCares?)

Hey @ATTCares

I recently placed an online order to switch to AT&T using BOGO deal (and $300 gift card offer for online orders). Initially AT&T couldn't port my  numbers. When I called to check the status of the order, sales rep told me that I need to cancel the old order and place a new one over the phone. Knowing that the $300 offer is only for online orders, I decided against it .... until the sales rep offered that I will get a $300 account credit after the accounts are activated. As verbal offers are worth nothing, I inquired what is the guarantee that I will get $300 account credit? I was told that sales rep will be adding a note to the account to document "the promise" that a $300 account credit has to be issued when accounts become activated. I check with the supervisor of the sales rep who confirms the note on the account. At that point we go ahead with the new order (and they cancel my older online order). After that I receive the phones, numbers are ported, lines are activated, first bill is issued and paid. At that point, I call the customer service and ask if they can add the promised credit. The rep is nice, she finds the note but says that she can't issue the account credit. "Only the sales rep can do that". I request if she can send a note to the sales team which she does. I waited 2 weeks, nothing happens. I call AT&T again. The customer service rep couldn't find the note on my account this time. I request to speak with her supervisor. She transfers the call, supervisor isn't available and I leave a message. No response. I wait another week. Then I called again. Third CS rep again can't find the note (for the promised $300 account credit). I ask to speak with supervisor who is luckily available this time. We spend a long time discussing the whole issue again. She didn't find the note initially (and tries her best to convince that no such credit exist). I request her to check notes on my account from the order date and read every word. Finally she finds the note. But the answer is again the same - she can't issue the refund. I asked if I can contact the sales rep directly. She told me, no. The best she can do is that she can send a "end of sales feedback" form to the sales team and hopefully they will look at it and process the promised credit. I wait again .... So basically I am now stuck. AT&T lured me in with a promise. I did my part and had them document the promise on my account. But still I don't see anything from AT&T. I don't know what to do next? Another call and another long talk with supervisor and another note to sales team isn't going to do much. I have already spent more than 8 hours on the phone for this issue. Any ideas?? Thanks